Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

r"
"
gm

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?m)(?:\.?)([\w\-_+#~!$&\'\.]+(?<!\.)@(?<!\.)[\w]+[\w\-\.]*\.[a-zA-Z-]{2,3})(?:[^\w])`) var str = `VALID EMAILS: davida@yahoo.com, davida-100@yahoo.com, davida.100@yahoo.com, davida111@davida.com, davida-100@davida.net, davida.100@davida.com.au, davida@1.com, davida@gmail.com.com, davida+100@gmail.com, davida-100@yahoo-test.com valid special char ~@davidalberto.com hey@ucl.ac.uk, "this..one"@gmail.com, h.e.y@gmail.com, the "." at the start should be ignored .davida@davida.com, suffix should be ignored davida@gmail.com.1a prefix should be ignored davida@davida@gmail.com, INVALID EMAILS: davida, davida@.com.my, davida123.@gmail.a, davida123@gmail.a, davida123@.com, davida123@.com.com, davida()*@gmail.com, davida@%*.com, davida.@gmail.com, tld is too long davida@gmail.comnnnnnnnn INVALID EMAILS - TODO: adjacent "." should not be valid davida..2002@gmail.com some images a@bg.png 1x@cover.gif HIDDEN EMAILS: somethingatgmail.com something at gmail.com something AT gmail.com asdf ( at ) gmail.com yoooo (at) gmail.com HIDDEN EMAILS - TODO: this at that dot com this [at] that [dot] com ----- ` for i, match := range re.FindAllString(str, -1) { fmt.Println(match, "found at index", i) } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Golang, please visit: https://golang.org/pkg/regexp/